1. Field of the Invention
Aspects of the present invention relate to a battery management system and method.
2. Description of the Related Art
In general, vehicles having only a conventional internal combustion engine are considered to be one of the primary causes of environmental pollution. Accordingly, in recent years, in order to decrease environmental pollution, electric vehicles and hybrid vehicles have been actively developed.
An electric vehicle uses an electric motor that is powered by electricity output from a battery having a plurality of rechargeable secondary cells. Since electric vehicles use a battery as a main power source, exhaust gas is not generated, and little operating noise is produced.
A hybrid vehicle is an intermediate stage between a conventional internal combustion engine vehicle and an electric vehicle. A hybrid vehicle uses two or more power sources, for example, an internal combustion engine and a battery-powered motor. At the present time, a hybrid vehicle that uses an internal combustion engine and a fuel cell, where electrical energy is directly generated by chemically reacting hydrogen and oxygen, and a hybrid vehicle that uses a battery and a fuel cell, are being developed.
The number of secondary cells included in a battery is increasing, in order to discharge and store more power. Therefore, a cell balancing control method that can efficiently manage a plurality of connected cells in such batteries is needed in a battery management system (hereinafter referred to as BMS).
When a battery includes a plurality of cells that are connected in series, balancing the cells is important. Such cell balancing refers to minimizing a difference between the voltages of the cells, to within an allowable range. Hereinafter, the balancing the cell voltages is referred to as “cell balancing.” Cell balancing is important for maintaining the life-span and power output of a battery.
During cell balancing, a conventional battery management system adds a predetermined value to a state of charge (SOC) value (the lowest cell voltage of a plurality of cell voltages), to determine a discharge completion voltage. Such a conventional battery management system uses the discharge completion voltage to balance the cells. However, there is a limitation in that cell balancing is performed using one discharge completion voltage. The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country, to a person of ordinary skill in the art.